Surgical device for correction of spinal deformities

ABSTRACT

The present invention relates generally to a surgical device for the correction of deformities of the spinal column and finds particular, although not exclusive, utility in devices which are surgically implantable. Presently known implantable surgical devices are unable to provide for the progressive correction of spinal deformities assisted by active movements of the human body without fusion of the involved part of the spinal column. The present surgical device comprises a spinal column straightening means for permitting the relative rotation of two substantially adjacent vertebrae about a common axis substantially only in opposite rotational directions.

CROSS-REFERENCE TO RELATED APPLICATION

The present non-provisional patent application is a continuation-in-partof application Ser. No. 13/133,405, filed Jun. 8, 2011, and entitledSURGICAL DEVICE FOR CORRECTION OF SPINAL DEFORMITIES, which isincorporated in full by reference herein. The present non-provisionalpatent application claims the benefit of priority of: foreign PatentApplication No. GB0822507.0, which is entitled SURGICAL DEVICE FORCORRECTION OF SPINAL DEFORMITIES and which was filed Dec. 10, 2008;foreign Patent Application No. GB0902416.7, which is entitled SURGICALDEVICE FOR CORRECTION OF SPINAL DEFORMITIES and which was filed Feb. 16,2009; foreign Patent Application No. GB0913457.8, which is entitledSURGICAL DEVICE FOR CORRECTION OF SPINAL DEFORMITIES and which was filedAug. 3, 2009, all of which are incorporated in full by reference herein.

FIELD OF THE INVENTION

The present invention relates generally to a surgical device for thecorrection of deformities of the spinal column and finds particular,although not exclusive, utility in devices which are surgicallyimplantable.

BACKGROUND OF THE INVENTION

At present, the surgical correction of deformities of the spinal columninvolves a surgical procedure for the insertion of fixation implantdevices, such as pedicle screws or hooks, to each vertebra followed byapplication of external forces to achieve the desired correction of theshape of the spinal column and attachment of the said fixation devicesto rigid rod-like elements to achieve permanent stabilisation of theinvolved part of the spinal column. Bone graft is also added to achievepermanent fusion of the same part of the spinal column.

Previous devices for correcting spinal deformities have involved thefixation of bone screws which connect to rods via pivoting connections,for example as described in WO-A2-2007/014119. Also, the use of ratchetmechanisms with spinal implants is known from WO-A2-2008/057861, WO2007/143709 and EP-A2-1051947. Although these arrangements increase theversatility and ease of application of implants used for spinalfixation, the application of all currently used implants and methods forsurgical correction of deformities of the spinal column results in theamount of correction of the deformity achieved during the surgicalprocedure often being limited. Furthermore, during application of allcurrent implants and methods for surgical correction of deformities ofthe spinal column the entire correction is achieved during the surgicalprocedure and no further degree of correction is possible thereafter asthe involved part of the spinal column is permanently fused. Theconsequences of this are the permanent loss of spinal motion andsubsequent increase of the mechanical loads to the adjacent mobilespinal segments frequently leading to wear of these segments.

One device, described in US-A1-2005/0261770, has various arrangements ofinterconnecting vertebral supports including pivoting and slidingarrangements between the components in an attempt to avoid fusion andpermanent loss of the mobility of the spinal column. However, suchimplants cannot be used as spinal deformity correcting devices as nomeans for adjusting the relative position of the vertebrae is provided.Other devices are described in US-A1-2006/155279, EP-A1-0667127,US-A1-2003/191470, U.S. Pat. No. 5,951,555, U.S. Pat. No. 5,672,175 andGB2412320 which include springs, flexible rods or other force-generatingmeans, such as memory alloys, attempt to prevent development of thedeformity or even to gradually correct a deformity of the spinal column.Although such disclosed devices are able to facilitate the developmentof corrective forces between parts of the spinal column most are passiveand are unable to provide for the progressive correction of spinaldeformities assisted by active movements of the human body. The presentinvention addresses this issue.

BRIEF SUMMARY OF THE INVENTION

In a first aspect, the invention provides a surgical device for thecorrection of deformities of the spinal column comprising a spinalcolumn straightening means for permitting the relative rotation of twosubstantially adjacent vertebrae about a common axis substantially onlyin opposite rotational directions. The surgical device may be arrangedsuch that, in use, the anterior edges of the end plates of twosubstantially adjacent vertebrae are substantially only permitted tomove either closer to one another or further apart from one another.Correspondingly, the posterior edges of the end plates of twosubstantially adjacent vertebrae may be substantially only permitted tomove either further apart from one another or closer to one another. Thespinal column straightening means, in one embodiment, is a spinal columnstraightener.

The term “substantially” is used here in the phrase “substantially onlypermitted to move either closer to one another or further apart from oneanother” because it is contemplated that there may be an element of“play” in the device such that a slight degree of opposite relativemovement occurs.

This device, which may be affixed to the posterior surfaces ofvertebrae, therefore allows one of two modes of operation. The first iswhere adjacent vertebrae are permitted to increase their separationtowards their front surfaces and/or reduce their separation towardstheir rear surfaces, thus straightening spines which are curvedforwardly. The second is where adjacent vertebrae are permitted todecrease their separation towards their front surfaces and/or increasetheir separation towards their rear surfaces, thus straightening spineswhich are curved rearwardly. Furthermore, because the devicesubstantially prevents rotation of the vertebrae in the oppositedirection (of whichever mode of operation is selected) the deviceprevents the curved nature of the spine from worsening or returning toits former bent form after straightening. Moreover, as the individualstretches upwardly, thus temporarily straightening the spine, the deviceallows the adjacent vertebrae to straighten relative to one another butwill prevent them from returning to the their previously curved form.Over time, an individual's curved spine may be corrected to one whichmore closely resembles a typical “straight” spine.

The term “substantially” is used with the phrase “only in oppositerotational directions” because it is contemplated that there may be anelement of “play” in the device such that the adjacent vertebrae mayrotate in the same direction. However, the amount of this commonrotational movement may be minor compared to the opposite rotationalmovement effected due to the individual's typical daily activities.

The surgical device may include rotation means for permitting therelative rotation of the two said substantially adjacent vertebrae. Thisrelative rotation may be about the common axis. In this regard, thecommon axis may be located within the spinal column and substantiallyoutside the surgical device. The rotation means may include a ratchetmeans. This ratchet means may be for permitting relative rotation of twosubstantially adjacent vertebrae about the common axis substantiallyonly in opposite rotational directions. The ratchet may comprise wellknown features such as a pawl and teeth. In at least one embodiment, therotation means is a rotation controller. The rotation controller mayinclude two, preferably but not exclusively, symmetrically positionedratchet means arranged on either side of the rotation controller.

The common axis, in use, may be substantially perpendicular to thelength of the spinal column. This axis may lie substantially parallel tothe intersection of the coronal and transverse planes.

The surgical device may include connection means for connecting with twobone fixing elements, each element fixable, in use, to each saidadjacent vertebra. In one embodiment, the connection means is connectionapparatus.

The bone fixing elements may comprise substantially parallellongitudinal axes, such that, in use, the longitudinal axes aresubstantially parallel to the intersection of the median and transverseplanes.

The common axis may, in use, be substantially perpendicular to the saidlongitudinal axes or intersection of the median and transverse planes.

The surgical device may further comprise rotation means for permitting,in use, the relative rotation of the two said adjacent vertebrae aboutan axis substantially parallel to the longitudinal axes of the bonefixing element, or intersection of the median and transverse planes.

The connection means may comprise a first male member and a first femalemember.

One of the two said bone fixing elements may comprise a second femalemember and the first male member may be connectable with this secondfemale member.

The first male member may be rotatably and/or slidably connectable withthe second female member.

The first female member may be connectable with a bone fixing element inan adjacent vertebra.

The first female member may be rotatably and/or slidably connectablewith the bone fixing element.

Either or both of the first and second female members may includepivoting means for either permitting or restricting relative angularmovement of any connected first male member or bone fixing element. Inone embodiment, the pivoting means is a pivot controller.

The surgical device may include one or more bone fixing elements.

The surgical device may include at least one bone fixing elementfixable, in use, to a first vertebra.

The surgical device may include alternative connection means forconnecting with another bone fixing element fixable, in use, to a secondadjacent vertebra.

The alternative connection means may comprise a first alternative femalemember and a first alternative male member.

The first alternative female member may be connectable with the firstalternative male member of an adjacent device.

The first alternative female member may be rotatably and/or slidablyconnectable with the first alternative male member of the adjacentdevice.

The first alternative female member may include pivoting means foreither permitting or restricting relative angular movement of anyconnected alternative male member or bone fixing element.

The first alternative female member and first alternative male membermay be on opposite sides of the ratchet means.

The surgical device may include means for connecting either directly orindirectly with an adjacent similar device. When connectable directlyone of the male members may be insertable into one of the femalemembers. When connectable indirectly another intermediate element may beinterposed therebetween. This intermediate element may comprise one ormore male members and one or more female members, although other meansof interconnection are contemplated. The intermediate element may be arod.

Additional articulating elements may be provided within the femalemembers shaped preferably, but not exclusively, in such a manner as toallow additional interposed articulations of the ‘ball-and-socket’ typeand of the ‘sliding’ type between the articulating elements and the maleand female members.

In one embodiment, the stem includes a longitudinal split along itslongitudinal axis. The split may extend along the entire length or alongonly part of its length. The split may be arranged preferably, but notexclusively, along the sagittal plane (when installed in use). It may atleast partially separate the stem into two limbs. In use the distance orseparation between the two limbs may be increased temporarily andreversibly. This separation may allow the ratchet(s) to be temporarilyovercome such that the angle between the stem and the bone fixingelement may be set during installation. After this step the separationof the two limbs may be reduced such the influence of the ratchet(s) isagain enforced over this angle.

In a second aspect, the invention provides a surgical device forcorrection of deformities of the spinal column comprising at least twomutually interconnectable segments arranged for affixation on at leasttwo separate vertebrae of the spinal column, each segment comprising afirst part, equipped with at least one bone fixing element adapted foraffixation on at least one vertebra of the spinal column, a second part,connectable to the said first part at an axially arranged connectionpermitting rotation of the said first and second parts relative to eachother around a first axis, the said second part also being equipped withat least one stem able to withstand mechanical loads during use, thesaid second part also being equipped with at least one connecting holeof design appropriate, firstly, to allow insertion of the said stem ofat least one other segment of the surgical device disclosed herein tothe said connecting hole and, secondly, to allow pivoting (angularmovement) and axial sliding of the said stem in the said connectinghole, a ratchet arrangement of the said axially arranged connectionbetween the said first and second parts permitting, in use, the saidfirst and second parts to rotate relative to each other around the saidfirst axis of rotation in a single predetermined direction butpreventing the said first and second parts from rotating around the saidfirst axis of rotation in an opposite direction, wherein, during use, atleast two mutually interconnected segments of the surgical devicedisclosed herein are affixed on at least two separate vertebrae of thespinal column, the said stem of the said second part of the segmentaffixed on the vertebra above being axially inserted in the saidconnecting hole of the said second part of the segment affixed on thevertebra below, permitting angular movements between the said twovertebrae of the spinal column in the desired direction of correction ofthe deformity but preventing any angular movement between the said twovertebrae of the spinal column in the opposite to the said desireddirection, and wherein, during normal daily activity or specialexercise-induced movements of the human spinal column, any loads appliedto the spinal column directed in a direction opposite to the saiddesired direction of correction of the said spinal deformity areendured, resisted and prevented by at least two mutually interconnectedsegments of the surgical device disclosed herein, whilst all other loadsare endured solely by the spinal column protecting thus the surgicaldevice disclosed herein from mechanical failure or loosening of itssecure affixation on a vertebrae of the spinal column, and whereby, overa period of time, gradual correction of the said spinal deformity can beachieved without additional force generating means.

As described herein there is provided a surgical device for gradualcorrection of deformities of the spinal column without fusion of theinvolved part of the spinal column. The device may comprise mutuallyinterconnected segments affixable to separate vertebrae of the spinalcolumn. Their arrangement may comprise a ratchet as part of a pivotingconnection between the part affixed to the bone and a support. Thesupport may have a connecting opening to permit free relative rotationand axial movement, but which may restrict relative angulatory movementat least in one plane, between the mutually interconnected segments.

The configuration of the surgical device may permit gradual angularcorrection of the relative position of the vertebrae while at the sametime all other movements, including those affected by axial loading ofthe spinal column are allowed. It is to be appreciated that gradualcorrection of a deformity of the spinal column may be achieved over aperiod of time following the application of the surgical device effectedby active and passive movements of the spinal column during normal dailyactivities and exercising while, at the same time, the mobility of allparts of the spinal column may be preserved.

The bone fixing elements described and/or claimed herein may be of thepedicle screw variety.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other characteristics, features and advantages of thepresent invention will become apparent from the following detaileddescription, taken in conjunction with the accompanying drawings, whichillustrate, by way of example, the principles of the invention. Thisdescription is given for the sake of example only, without limiting thescope of the invention. The reference figures quoted below refer to theattached drawings.

FIG. 1 is a perspective view of a device according to a first embodimentof the invention;

FIG. 2 is a perspective view of two of the devices of FIG. 1 in use withvertebrae;

FIG. 3 is a cross-sectional side view of a series of devices accordingto a second embodiment of the invention in use with a series of adjacentvertebrae;

FIG. 4 is a perspective view of a device according to a third embodimentof the invention;

FIG. 5 is a perspective view of a device according to a fourthembodiment of the invention;

FIG. 6 is a close-up perspective view of the device of FIG. 5;

FIG. 7 is a perspective view of two of the devices of FIG. 5 in use withtwo vertebrae;

FIG. 8 is a close-up perspective view of the two devices of FIG. 7;

FIG. 9 is a perspective view of a device according to a fifth embodimentof the invention;

FIG. 10 is a perspective view of a device according to a sixthembodiment of the invention;

FIG. 11 is a perspective view of a device according to a seventhembodiment of the invention;

FIG. 12 is a perspective view of the device of FIG. 11 with analternative feature;

FIG. 13 is a perspective view of a device according to an eighthembodiment of the invention;

FIG. 14 is a rear elevational view of the device of FIG. 13;

FIG. 15 is a perspective view of a device according to an ninthembodiment of the invention; and

FIG. 16 a perspective view of a device according to a tenth embodimentof the invention.

FIG. 17 is a perspective view of a device according to an eleventhembodiment of the invention.

FIG. 18 is a partial view of a device according to a twelfth embodimentof the invention.

FIG. 19 is a perspective view of a device according to a thirteenthembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described with respect to particularembodiments and with reference to certain drawings but the invention isnot limited thereto but only by the claims. The drawings described areonly schematic and are non-limiting. In the drawings, the size of someof the elements may be exaggerated and not drawn to scale forillustrative purposes. The dimensions and the relative dimensions do notcorrespond to actual reductions to practice of the invention.

Furthermore, the terms first, second, third and the like in thedescription and in the claims, are used for distinguishing betweensimilar elements and not necessarily for describing a sequence, eithertemporally, spatially, in ranking or in any other manner. It is to beunderstood that the terms so used are interchangeable under appropriatecircumstances and that the embodiments of the invention described hereinare capable of operation in other sequences than described orillustrated herein.

Moreover, the terms top, bottom, over, under and the like in thedescription and the claims are used for descriptive purposes and notnecessarily for describing relative positions. It is to be understoodthat the terms so used are interchangeable under appropriatecircumstances and that the embodiments of the invention described hereinare capable of operation in other orientations than described orillustrated herein.

It is to be noticed that the term “comprising”, used in the claims,should not be interpreted as being restricted to the means listedthereafter; it does not exclude other elements or steps. It is thus tobe interpreted as specifying the presence of the stated features,integers, steps or components as referred to, but does not preclude thepresence or addition of one or more other features, integers, steps orcomponents, or groups thereof. Thus, the scope of the expression “adevice comprising means A and B” should not be limited to devicesconsisting only of components A and B. It means that with respect to thepresent invention, the only relevant components of the device are A andB.

Similarly, it is to be noticed that the term “connected”, used in thedescription, should not be interpreted as being restricted to directconnections only. “Connected” may mean that two or more elements areeither in direct physical or that two or more elements are not in directcontact with each other but yet still co-operate or interact with eachother.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment of the present invention. Thus, appearances of the phrases“in one embodiment” or “in an embodiment” in various places throughoutthis specification are not necessarily all referring to the sameembodiment, but may refer to different embodiments.

Furthermore, the particular features, structures or characteristics maybe combined in any suitable manner, as would be apparent to one ofordinary skill in the art from this disclosure, in one or moreembodiments.

Similarly it should be appreciated that in the description of exemplaryembodiments of the invention, various features of the invention aresometimes grouped together in a single embodiment, figure, ordescription thereof for the purpose of streamlining the disclosure andaiding in the understanding of one or more of the various inventiveaspects. This method of disclosure, however, is not to be interpreted asreflecting an intention that the claimed invention requires morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive aspects lie in less than allfeatures of a single foregoing disclosed embodiment. Thus, the claimsfollowing the detailed description are hereby expressly incorporatedinto this detailed description, with each claim standing on its own as aseparate embodiment of this invention.

Furthermore, while some embodiments described herein include some butnot other features included in other embodiments, combinations offeatures of different embodiments are meant to be within the scope ofthe invention, and form different embodiments, as would be understood bythose skilled in the art. For example, in the following claims, any ofthe claimed embodiments can be used in any combination.

In the description provided herein, numerous specific details are setforth. However, it is understood that embodiments of the invention maybe practised without these specific details. In other instances,well-known methods, structures and techniques have not been shown indetail in order not to obscure an understanding of this description.

The invention will now be described by a detailed description of severalembodiments of the invention. It is clear that other embodiments of theinvention can be configured according to the knowledge of personsskilled in the art without departing from the true spirit or technicalteaching of the invention, the invention being limited only by the termsof the appended claims.

In FIG. 1 a surgical device 10 for the correction of deformities of thespinal column includes a rotation means 11 (substantially cylindrical inshape) for allowing rotation between two elements; the two elementsbeing a stem, or male member, 12 and a means 18 of connecting with abone-fixing element 30. The stem 12 is substantially cylindrical. Inthis embodiment, the means 18 of connecting with the bone fixing element30 is a socket, or female member, 16 arranged on an arm radiating awayfrom the means 11 for allowing rotation.

The rotation means 11 includes a ratchet mechanism 20 which permits thetwo sides of the rotation means 11 to only rotate in opposite directionsrelative to one another about a common axis referenced “A”. In FIG. 1,the arrow referenced “B” indicates the direction in which the bonefixing element 30 is permitted to rotate, and the arrow referenced “C”indicates the direction in which the stem 12 is permitted to rotate. Theangle between the longitudinal axis of the stem 12 and the longitudinalaxis of the bone fixing element 30 is indicated “Φ”. In use, the bonefixing element 30 and the stem 12 may only rotate in opposite directionssuch that the angle Φ may increase but not decrease. This restriction iseffected by the ratchet 20.

The bone fixing element 30 comprises a shaft 32 having a screw thread 34at one end and a head 36 at the other end. The head 36 is larger thanthe shaft 32 and of the socket 16 thus preventing the rotation means 11from slipping off the bone fixing element 30.

The shaft 32 of the bone fixing element 30 may rotate within the socket16 thus allowing, in use, sideways flexing (in the coronal plane) of thespinal column. The bone fixing element 30 includes a socket, or femalemember, in the head 38. This will be explained in more detail below.

FIG. 2 shows two devices 10 in use together with two adjacent vertebrae40, 42. The bone fixing elements 30 have been screwed into each vertebra40, 42 such that each device 10 is held captive thereto by the heads 36of the respective bone fixing elements 30. The stem 12 of the upperdevice 10 has been inserted into the socket 38 of the bone fixingelement 30 holding the lower device 10 captive. The stem 12 may rotateand move axially within the socket 38 thus allowing a certain amount offreedom of movement between adjacent vertebrae other than thatrestricted by the ratchet 20.

The socket 38 in head 36 of the upper bone fixing element 30 may receivea stem 12 of another device 10 (not shown) attached to a vertebra above(not shown). Likewise, the stem 12 of the lowermost device 10 may bereceived in the socket 38 of another device 10 (not shown) attached to avertebra below (not shown).

Because of the ability for the various elements (bone fixing shaft 32and socket 16; stem 12 and socket 38) to move relative to one another inone or more directions and/or planes as necessary, due to an arrangedtolerance in the respective male and female members, the actualvertebrae 40, 42 do not rotate about the axis A (in FIG. 1).

Rather, they will rotate about the natural axes of the vertebrae, whichwill lie substantially in the sagittal, transverse and coronal planes.

A series 100 of devices 110 may be affixed to a series of vertebrae 40,42, 44, 46, 48 forming a portion of a spinal column as shown in FIG. 3.These devices 110 are slightly different to the devices 10 describedabove but operate in a similar manner. They each include a rotationmeans 111 (substantially cylindrical in shape) for allowing rotationbetween a bone fixing element 130 and a stem 112. Each stem 112 isinserted into the device 110 below.

In this way the angle Φ may be increased but not substantiallydecreased. This means that the vertical gap “D” between the front edgesof adjacent vertebrae may be increased but not substantially decreased.

A third embodiment of the device 210 is shown in FIG. 4. It comprises astem 212 attached to one side 214 of a rotational ratchet 220, and abone fixing element 230 comprising a screw thread 234 and a shaft 232directly attached to the other side 218 of the ratchet 220. The twosides 214, 218 make up the rotation means 211 (which is substantiallycylindrical in shape). The ratchet 220 restricts relative rotationalmovement of the two sides in a similar manner to that described above.

In this embodiment, a socket 238 is provided in the body of the rotationmeans 211. This socket may receive a stem 212 from an adjacent device210, in a similar manner to that described above, such that an array ofdevices 210 may be interconnected. The socket 238 is arranged such thatthe stem 212 may rotate and move axially and angularly within it thusallowing a certain amount of freedom of movement between adjacentvertebrae other than that restricted by the ratchet 20.

A fourth embodiment of the device 310 is shown in FIG. 5. This device310 is similar to the device 210 shown in FIG. 4 except that the shaft332 of the bone fixing element 330 is not directly attached to therotation means 311, which is substantially cylindrical in shape. Rather,a socket 316 is provided in the body of the rotation means 311 adjacentthe socket 338 for receiving the stem 312 of an adjacent device 310.This socket 316 may receive the shaft 332 of the bone fixing element330. The socket 316 is arranged such that the stem 312 may rotate andmove axially and angularly within it thus mallowing a certain amount offreedom of movement between adjacent vertebrae other than thatrestricted by the ratchet 20. This is more clearly shown in FIG. 6.

The axial movement is referenced “F”, the rotational movement isreferenced “E”, and the angular movement is referenced “G”. All otherfeatures are the same as described with regard to FIG. 5.

FIG. 7 shows two devices 310 arranged together, and connected or affixedto two adjacent vertebrae 40, 42, such that the stem 312 of the upperdevice 310 is inserted into the socket 238 of the lower device 310. Thearrow referenced “H” indicates the direction in which the uppervertebrae 40 may rotate relative to the axis of rotation “A”. FIG. 8indicates the rotational “I”, axial “J” and angular “K” movement whichthe upper stem 312 may make relative to the lower socket 338. There mayalso be some rotational movement therebetween (not shown).

A different embodiment of the device 410 is shown in FIG. 9. This device410 has a rotation means 411 (substantially cylindrical in shape)comprising two ratchets 420 a, 420 b separating the rotation means 411into three portions. At each end portion of the rotation means 411 astem 412 a, 412 b is provided projecting radially away. A socket, orfemale member, 416 is provided radially through the middle portion ofthe rotation means 411. This socket 416 may receive a shaft 432 of abone fixing element 430 (refer to FIG. 10) such that it may be affixedto vertebra. Each stem 412 a, 412 b may be connected to a bone fixingelement 43 either directly or indirectly. An example is shown in FIG.10. The device 450 comprises a substantially cylindrical elementcomprising two sockets, or female members, 438, 456 which pass radiallythrough the cylindrical element from one side to the other. These twosockets 438, 456 are aligned such that their respective bores aresubstantially perpendicular to one another. The shaft 432 of a bonefixing element is shown inserted into one of the sockets 456. The othersocket 438 may receive one of the stems 412 a, 412 b described above.Two devices 450 may be arranged one on each stem 412 a, 412 b. By virtueof ratchet 420 a the upper bone fixing element, in device 450, and theone in the rotation means 411 may rotate relative to one another butonly in opposite directions. Also, by virtue of ratchet 420 b the lowerbone fixing element, in another device 450, and the one in the rotationmeans 411 may rotate relative to one another but only in oppositedirections.

The relative rotation of the two sets of bone fixing elements 430 mayrotate around a common axis referenced “L” passing through thelongitudinal central axis of the substantially cylindrical rotationmeans 411.

FIG. 11 shows yet another embodiment of the device 510. This device 510includes a bone fixing element 530 rotatably connected to one side of arotation means 511. On the other side of the rotation means 511 a stem,or male member, 512 is provided. The stem 512 and bone fixing element530 may rotate relative to one another limited by some means, possibly aratchet means (not shown), such that they may only rotate away from eachother (as shown in the Figure) so that angle Φ may be increased but notsubstantially decreased.

A socket, or female member, 538 is provided with the rotation means 511for receiving a stem 512 from an adjacent device 510 as shown in FIG.12. The position of the socket 538 is arranged substantially on the sameaxis as the longitudinal length of the bone fixing element 530. However,the longitudinal axis/direction of the bore of the socket 538 issubstantially perpendicular to the longitudinal axis of the bone fixingelement 530.

This Figure, (bone fixing element 530 removed for clarity purposes) alsoincludes a variant to the device 510 shown in FIG. 11 in that the socket539 is a ball socket. This allows angular as well as axial androtational movement of the stem 512 of the adjacent device 510 relativeto the device 510.

Another embodiment is shown in FIGS. 13 and 14. This device 610 issimilar to the device 510 described above, having a rotation means 611and a bone fixing element 634. However, the socket 638 for receiving thestem 612 of an adjacent device 610 is arranged to one side of the bonefixing element 634 as is more clearly shown in FIG. 14. This view isfrom “behind” the device 610 looking along the length of the bone fixingelement 634. The socket 638 is arranged on the other side of the ratchetmeans 620 from the bone fixing element 634 and has its boresubstantially perpendicular to the longitudinal length of the bonefixing element 634.

A ninth embodiment is shown in FIG. 15. This embodiment 710 comprises abone fixing element 730 which comprises a thread 734, a shaft 732 and ahead 736. The head includes a socket 736 for receiving the stem 712 ofan adjacent device 710. The stem 712 is attached to, or integral withone half 717 of the rotation means 711. This rotation means permitsrelative rotation between the stem 712 and the bone fixing element 730around an axis which substantially lies long the intersection of thetransverse and coronal planes. The rotation means 711 comprises a body717 at the base of which the stem 712 is connected and at the upper endof which two arms 718, 719 are provided. The other half of the rotationmeans 711 comprises a body 721 on which are provided two axles or pins715 (only one being shown) around which the two arms 718, 719 arearranged thus allowing relative rotation of the two halves 717, 721.

The body 721 also includes a female socket 716 through which the shaft732 of the bone fixing element 730 is arranged allowing relativerotational movement between the bone fixing element 730 and the stem 712about the longitudinal axis of the bone fixing element 730.

The rotation means 711 includes a ratchet 720 which in this casecomprises a set of teeth on one of the two halves 717, 721 and a pawl onthe other of the two halves. It is possible that the pawl is another setof teeth, the sets of teeth arranged and provided to allow them to slideover one another in one direction but prevent them sliding over oneanother in the other direction.

FIG. 16 shows an embodiment 810 which is similar to the ninth embodimentdescribed in conjunction with FIG. 15. The only difference is thatdevice 810 includes a means for attaching another transverse stem 813 tothe head 836 of the bone fixing element 830. Alternatively, thetransverse stem may be integral with the head 836.

Another bone fixing element 830 is provided in the same vertebra 40 andarranged laterally to one side of the other. The transverse stem 813connects the heads 836 of the two bone fixing elements 830. In this waygreater stability is provided to the structure and to the spinal column.It should be understood that the concept of an additional bone fixingelement 830 and interconnection between the two bone fixing elements 830in the same vertebra may be applied to any of the other embodimentsdescribed herein.

In the foregoing description of the various embodiments, it has beenexplained how the angle Φ may increase but not decrease. It is to beunderstood that the opposite effect is also possible, namely that theangle Φ may decrease but not increase. This restriction may be effectedby appropriate arrangement of the ratchet as required.

Although when describing the various sockets, or female members, 38,238, 316, 338, 416, 456, 438, 538, 539, 638 it has been explained thatthey are arranged to allow relative rotational, axial and angularmovement with the stem or shaft it should be understood that in someembodiments it may be desirable to limit or even restrict some or all ofthis allowance. It is possible to include means, such as contouredsurfaces, for permitting only relative movement between the stem, and/orshaft, and socket in one or more directions (axial, rotational, angular)and/or planes (sagittal, coronal, transverse).

For instance it may be preferred to restrict relative angulatorymovement in one or more planes such as the sagittal plane.

Any of the embodiments described herein may include a ball joint in anyof the female sockets.

Furthermore, although not all of the bone fixing elements 30, 330, 430are shown including a head of greater size than the socket through whichthey may be inserted it is to be understood that they may include such ahead to prevent them from disengaging with their corresponding devicesand/or rotation means.

An eleventh embodiment of the invention is shown in FIG. 17. This device910 is similar to the device 10 shown in FIG. 1 insofar as the device910 includes a rotation means 911 allowing rotation between twoelements; the two elements being a stem, or male member, 912 and a means918 of connecting with a bone-fixing element 930. The stem 912 isbifurcated at one end into two arms 913 between which the means 918 forconnecting with a bone fixing element (also known as the bone fixingelement root holder), is held. However, in this embodiment, the rotationmeans 911 includes a curved ratchet mechanism 920 which permits the twoelements 912 and 918 of the rotation means 911 to only rotate inopposite directions relative to one another about a common axisreferenced “A” which lies substantially outside the device 910 andpreferably, but not exclusively, anterior to the device 910. It will beappreciated by those skilled in the art that the arrangement of placingthe common axis of rotation “A” anterior to the device 910 approximatesthe common axis of rotation “A” to the natural axis of rotation of thevertebrae of the spine and significantly facilitates the rotationalfunction of the device 910. Axis “A” may lie substantially parallel tothe intersection of the transverse and coronal planes.

The term “curved” is used to describe that the ratchet teeth may bearranged in an arc, being a portion of a circle, subtending an angle ofbetween 5 and 90 degrees.

In this embodiment, one set of teeth of the ratchet 920 is positioned onthe outer surface of the bone fixing element root holder 918, and theother set is positioned on the inside surface of one of the arms 913. Itis possible (but not shown in FIG. 17) that another ratchet is providedbetween the other arm 913 and the other side of the bone fixing elementroot holder 918.

FIG. 18 shows a portion of a device 1010 according to a twelfthembodiment of the invention. This device 1010 includes a bone fixingelement 1030 similar to the bone fixing element 30 shown in FIG. 1 and asocket, or female member, 1038 similar to the socket, or female member,38 in the bone fixing element 30 shown in FIG. 1. The stem 1012, similarto the stem 12 shown in FIG. 1, is not shown for the sake of clarity.Connection between two adjacent devices is provided by inserting thestem 1012 of an adjacent device (shown only partially here for clarity)into the socket, or female member, 1038 in a manner similar to themanner illustrated in FIG. 2.

In this embodiment an articulating element 1057 is provided within thesocket, or female member, 1038 of the bone fixing element 1030. Thearticulating element 1057 is arranged preferably, but not exclusively,between the anterior edge of the stem 1012 and the internal surface ofthe socket, or female member, 1038 and shaped preferably, but notexclusively, in a such manner as to allow ‘ball-and-socket’ typerotational articulation between 1058 the anterior surface of thearticulating element 1057 and the internal surface of the socket, orfemale member, 1038 and ‘sliding’ type articulation 1059 between theposterior surface of the articulating element 1057 and the anteriorsurface of the stem 1012. It will be appreciated by those skilled in theart that the arrangement of providing an articulating element 1057within the socket, or female member, 1038 of the bone fixing element1030 allows angular as well as axial and rotational movement of the stem1012 within the socket, or female member, 1038 of the bone fixingelement 1030 and, at the same time, reduces significantly thedevelopment of contact stresses on the contact surfaces during use.

A thirteenth embodiment of the invention is shown in FIG. 19. Thisdevice 1110 is similar to the device 10 shown in FIG. 1 insofar as thedevice 1110 includes a rotation means 1111 allowing rotation between twoelements; the two elements being a stem, or male member, 1112 and ameans 1118 of connecting with a bone-fixing element 1130 (otherwiseknown as a bone fixing element root holder). However, in this embodimentthe rotation means 1111 includes two separate and preferably, but notexclusively, symmetrically positioned ratchet mechanisms 1120 a and 1120b which permit the two elements 1112 and 1118 of the rotation means 1111to only rotate in opposite directions relative to one another about acommon axis.

The male member 1112 bifurcates into two arms 1113 at its upper endbetween which the rotation means 1111 is located.

In this embodiment, the stem 1112 includes a longitudinal split 1160provided through its longitudinal length. In this Figure the split 1160is shown extending from the male member's upper end, at a point wherethe two arms 1113 commence, almost all the way to the distal and lowestend. It is to be understood that different devices may be provided withdifferent length splits, as required. The two sides of the longitudinalsplit 1160 are shown approximately parallel to the sagittal plane. Otherorientations are contemplated. It will be appreciated by those skilledin the art that the arrangement of the longitudinal split 1160 throughthe stem 1112 allows, in use, the two arms 1113 to be moved apart andaway from one another in the directions indicated by the arrowsreferenced 1161 a and 1162 b. With the two arms 1113 moved in thismanner the two sets of teeth in each ratchet 1120 a, 1120 b will becomedisengaged such that the bone fixing element 1130 may be rotatedrelative to the male member 1112. When the desired angle therebetweenhas been reached, the two arms 1113 may be moved back towards together(in direction opposite to those referenced 1162 a 1162 b. In thisregard, the material composition of the male member 1112 may be selectedto provide a degree of resilience such that the two arms 1113 aremaintained in relatively close relationship (such that the ratchet teethare engaged) without any force being imparted thereon. The arms 1113 mayspring back to this position after being held temporarily apart.

In one embodiment, the split may extend from one end to the other of themale member 1112 and connecting means for releasably retaining the twomale member halves together may be provided. For instance, a clip,spring, bungee or other such connecting means may be employed.

1. A surgical device for the correction of deformities of the spinalcolumn comprising a spinal column straightener having two bone fixingelements each attachable to a vertebra of a spinal column, and aconnection apparatus for connecting the two bone fixing elements, theconnection apparatus including a stem and a female socket for connectingwith at least one of said bone fixing elements, and a rotationcontroller for permitting relative rotation of the two bone fixingelements about a common axis, wherein the rotation controller includes aratchet such that the two bone fixing elements are permitted to rotateabout a common axis parallel to the intersection of the coronal andtransverse planes substantially only in opposite rotational directionsso that over a period of time following the installation of the two bonefixing elements into two substantially adjacent vertebrae and theconnection together of the two bone fixing elements with the connectionapparatus, and effected by active and passive movements of the spinalcolumn during normal daily activities and exercising, gradual correctionof a deformity of the spinal column is achievable by substantially onlypermitting the anterior edges of the end plates of the two substantiallyadjacent vertebrae to move either closer to one another, or furtherapart from one another.
 2. The surgical device of claim 1, wherein thecommon axis, in use, is substantially perpendicular to the length of thespinal column.
 3. The surgical device of claim 1, wherein the commonaxis lies substantially outside the said device.
 4. The surgical deviceof claim 1, wherein the bone fixing elements comprise substantiallyparallel longitudinal axes, in use, and the common axis is, in use,substantially perpendicular to said parallel longitudinal axes.
 5. Thesurgical device of claim 1, wherein the rotation controller is arrangedto permit, in use, the relative rotation of the two said substantiallyadjacent vertebrae about an axis substantially parallel to thelongitudinal axes of the bone fixing element.
 6. The surgical device ofclaim 1, wherein the rotation controller includes two ratchet mechanismsdisposed separately and at either side thereof.
 7. The surgical deviceof claim 1, wherein one of the two said bone fixing elements comprises abone fixing element socket and the stem is connectable with this bonefixing element socket.
 8. The surgical device of claim 1, wherein thestem includes a longitudinal split at least partially separating thesaid stem into two halves.
 9. The surgical device of claim 7, whereinthe stem is rotatably and/or slidably connectable with the bone fixingelement socket.
 10. The surgical device of claim 1, wherein the femalesocket is connectable with the bone fixing element in an adjacentvertebra.
 11. The surgical device of claim 10, wherein the female socketis slidably and/or rotatably connectable with the bone fixing element.12. The surgical device of claim 7, wherein either or both of the femalesocket and bone fixing element socket include a contoured surface foreither permitting or restricting relative angular movement of anyconnected stem or bone fixing element.
 13. The surgical device of claim7, wherein an articulating element is provided within the bone fixingelement socket, for permitting relative rotational and/or slidingmovement between a connected stem and the bone fixing element.
 14. Amethod for surgically correcting deformities of the spinal column, themethod comprising: affixing two bone fixing elements to two adjacentvertebra of a spinal column; connecting the two bone fixing elementswith a connection apparatus, the connection apparatus including a stemand a female socket, and a rotation controller; wherein the rotationcontroller includes a ratchet such that it permits relative rotation ofthe two bone fixing elements about a common axis parallel to theintersection of the coronal and transverse planes substantially only inopposite rotational directions so that over a period of time followingthe affixing of the two bone fixing elements and effected by active andpassive movements of the spinal column during normal daily activitiesand exercising, gradual correction of a deformity of the spinal columnis achievable by substantially only permitting the anterior edges of theend plates of the two substantially adjacent vertebrae to move eithercloser to one another, or further apart from one another.
 15. The methodof claim 10, further comprising: providing one of the two said bonefixing elements with a bone fixing element socket; connecting the stemwith this bone fixing element socket; and providing suitable contouredsurfaces for either or both of the female socket and bone fixing elementsocket to either permit or restrict relative angular movement of anyconnected stem or bone fixing element.